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Characterisation and ageing of a water ultrafiltration membrane

Abstract : During disinfections, water ultrafiltration membranes are mechanically and chemically stressed. These stresses lead to an early membrane ageing implying a drop of the quality of ultrafiltrated water. The aim of this study is to examine the long term behaviour of an ultrafiltration polysulfone hollow fibre in contact with bleach. After the initial characterisation of the fibre and its main component (polysulfone), we broached watermembrane physical interaction. The sorption behaviour of this asymmetric membrane could be interpreted within a dual mechanism constituted of two simultaneous phenomena: pore filling and water absorptiondiffusion in the pore walls. As chemical ageing could induce large modifications on membranes interaction and transport properties, we studied these phenomena via structure-properties relationships. The bleach-membrane chemical interaction shows a degradation of the polysulfone, in spite its well-known chemical stability. The degradation, which generates an embrittlement of the fibre, occurs by chains scission (determined by Size Exclusion Chromatography) with the hydroxyl radical - OH formed in the bleach solution. These chain scissions take place on the isopropylidene and sulfone groups to form final vinylidene and sulfonate groups respectively. Analytic investigations (IR and proton NMR) show that the degradation of additives happens separately without interfering on the ageing of the PSU but alters the behaviour of the fibre. The lifetime of the fibre depends on the total chlorine concentration of the ageing solution but also on its pH which drives the formation of hypochlorous acid and hypochlorite ion in great proportion, essential condition for the formation of hydroxyl radicals.
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https://pastel.archives-ouvertes.fr/pastel-00001528
Contributor : Ecole Arts Et Métiers Paristech <>
Submitted on : Tuesday, January 3, 2006 - 8:00:00 AM
Last modification on : Wednesday, July 25, 2018 - 1:23:46 AM
Long-term archiving on: : Thursday, September 30, 2010 - 6:54:44 PM

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Emmanuelle Gaudichet-Maurin. Characterisation and ageing of a water ultrafiltration membrane. Engineering Sciences [physics]. Arts et Métiers ParisTech, 2005. English. ⟨NNT : 2005ENAM0019⟩. ⟨pastel-00001528⟩

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